The invention relates to a device for strapping, especially for longitudinally strapping packaged material with a strap, comprising a strap roll, from which strapping, which is to be processed, is pulled with formation of a strap storage system for a subsequent strapping process.
Such a device is known, for example, from DE 200 07 232 U1. For this device, the packaged material, which is to be strapped, such as a stack of catalogs or newspapers, is placed by a preparing facility, the details of which are not described, on the device table. In or at the preparing table, a strapping roll is provided, from which the strapping is pulled off into a strap storage system, in which it is guided in a meandering fashion and runs into an injection device, by means of which it is injected into a channel-like strap-guiding frame embracing the packaged material. The free front end of the strap is captured once again and passed into a welding device where, after being stretched around the packaged material, for which purpose the strap is taken from the strap-guiding frame, it is welded, after which it is cut off. The strap is pulled by the injection process from the strap roll and the strap storage system is filled continuously, so that sufficient unrolled strapping for an injection process is always available in the strap storage system.
Known strapping devices have an automatic strap infeed. This means that the strapping is pulled automatically from the strap roll and conveyed to the storage system, where it is deposited in meandering fashion. For this purpose, a devise for determining the weight of the strap in the storage system is usually provided and frequently constructed as a rocker and controlled over the strap infeed. If the supply of strap is inadequate, the rocker, over suitable switching means, switches on the strap infeed and strap is passed automatically from the strop roll to the storage system. When a specified degree of filling and, with that, a corresponding weight of strap are attained, the rocker tilts and the switching means switch off the strap infeed. The strap infeed thus is controlled by the position of the rocker. As a rule, the storage system contains three to four times the length of strap for a strapping process. The equipment costs for this known strap infeed are appreciably high. Malfunctioning of the rocker is possible so that, at times, the whole of the infeed operation does not function properly.